If all the edge weights of an undirected graph are positive, then any subject of edges that connects all the vertices and has minimum total weight is a

Let $$G$$ be the simple graph with 20 vertices and 100 edges. The size of the minimum vertex cover of $$G$$ is 8. Then, the size of the maximum independent set of $$G$$ is:

Let $$G$$ be a simple connected planar graph with 13 vertices and 19 edges. Then, the number of faces in the planar embedding of the graph is:

What is the maximum number of edges in an acyclic undirected graph with $$n$$ vertices?